Hold-down device for multiconductor stringing blocks

ABSTRACT

Holddown device for attachment to multiconductor stringing blocks comprising mounting bracket attachable to upper part of bundle block frame, auxiliary bracket pivoted on mounting bracket and rotatably supporting holddown roller in operative position in throat of block to limit upward movement of pulling line and swingable upwardly to carry roller to inoperative position to provide clearance for running board through the block, spring means interconnecting the mounting and auxiliary brackets to apply a constraining force along a line shiftable to opposite sides of the pivot therebetween to resiliently urge holddown roller toward and maintain same in both operative and inoperative positions, and guide means for preventing contact of the pulling line simultaneously with its guide groove in the bundle block sheave and the holddown roller when latter is in operative position.

United States Patent [72] Inventors Frank Ward Reilly, Sr. 3,145,973 8/1964 MacFarlane 254/134.3PA

Lookout Mountain;

, Primary Exammer- Robert C. Riordon 3 :3 Bowman Chattanooga both Assistant Examiner-David R. Melton 1 pp No 855,264 Attorney-Davis, Lucas, Brewer & Brugman [22] Filed Sept. 4, 1969 [45] Patented June 15, 1971 [73] Asslgnee 1 f f ABSTRACT: Holddown device for attachment to multicon- C gamma ductor stringing blocks comprising mounting bracket attachable to upper part of bundle block frame, auxiliary bracket [54] HOLD DOWN DEVICE FOR MULTICONDUCTOR pivoted on mounting bracket and rotatably supporting holddown roller in operative position in throat of block to limit up- STRINGING BLOCKS ward movement of pulling line and swingable upwardly to 10 Claims, 5 Drawing Figs.

carry roller to inoperative position to provide clearance for U.S. unning board through the block, spring means interconnect.

ing the mounting and auxiliary brackets to apply a constrain- [5 llll- Cl. force along a line shiftable to opposite sides of the pivot of Search u therebetween to resiliently urge holddown roller toward and K1343 PA, 193,197 maintain same in both operative and inoperative positions, and guide means for preventing contact of the pulling line [56] Rekrences Cited simultaneously with its guide groove in the bundle block UNITED STATES PATENTS sheave and the holddown roller when latter is in operative 3,077,337 2/1963 Cronkright 254/134.3PA position.

if! 34 g5 22 29 g1} 31 f w l at F i'i K tL PATENTED JUNI 5 l97| sum 1 or 3 -42 Adel alora:

HOLD-DOWN DEVICE FOR MULTICONDUUI'UK STRINGING BLOCKS BACKGROUND OF THE INVENTION Transmission of high voltage electric energy has developed to the use of multiple lines or conductors, preferably two, three or four in number, which are erected or strung simultaneously for group suspension from and attachment to towers or supporting ground structures with the aid of multiconductor or bundle-stringing blocks. These blocks usually are suspended from the lower ends of line supporting insulators attached to the supporting structures and have roller or sheave means with a center groove for receiving an erection or pulling line and laterally spaced grooves for respectively receiving the conductors. A running board which may be similar to that disclosed in US. Letters Pat. No. 3,01 1,765 interconnects the pulling line and the conductors and normally functions to place the conductors in their respective bundle block grooves as it passes through the throat portion of each block, the pulling line being guided by the center grooves of the blocks.

Under some stringing conditions, as between crests of ridges with a supporting ground structure or structures being located in a valley between the ridges, the pulling line will-be lifted out of the center-guiding groove of the bundle-stringing block attached to the lower supporting structure by an upwardly directed component of the pulling force. This may require those lower blocks to be tied down to a ground anchor or their supporting structure, but whether or not such is true, the guiding function of the center groove of the block is morelikely than not to result.

A suggested solution was a holddown roller attached to the frame and disposed in a fixed position in the throat of the bundle block, but this was required to be spaced a sufficient distance above the main roller to provide clearance for'the running board to pass through the throat of the block. Consequently, such would fail to prevent misalignment of the running board with respect to the block and misplacement of the pulling line into one of the grooves of the main roller for receiving and guiding a conductor, since conditions obtain wherein the pulling line is disposed in the space between the holddown roller and the main roller and will be oscillating and floating both vertically and horizontally within that space. The resulting damage to the stringing block by the misaligned running board is serious, but even more serious is the complete destruction of a section of the conductors that might well follow or the surface damage to a conductor subsequently engaging a groove in which foreign matter has thus been deposited by the usually dirty pulling line, the latter being of major importance in the case of conductors used on extra high voltage transmission lines.

SUMMARY OF THE INVENTION This invention eliminates the difficulties and disadvantages which render such devices inoperative in a practical sense, under stringing conditions which cause the pulling line to be lifted from its guiding groove in a bundle block, by providing a holddown device for attachment to a multiconductor stringing block which limits vertical and lateral movement of the pulling line relative to the main roller to so confine it as to prevent serious misalignment of the running board and block and any contact between the pulling line and the conductor-receiving grooves, while not interfering with passage of the running board through the block.

More specifically, the invention comprises a holddown device having a frame attachable to a bundle block for rotatably supporting a holddown roller in the throat of the block in an operative position to limitedly guide a pulling line and readily movable automatically by contact with a running board toward an inoperative position to permit free passage of the running board through the block, with means for resiliently constraining the holddown roller toward such operative and inoperative positions. The invention also contemplates the use of auxiliary guide means for preventing contact of the pulling line simultaneously with the holddown and main rollers to preclude trapping or jamming of the line betweentheir two counter-rotating surfaces which could occur if the block has moved or yawed about its vertical axis or the pulling line for any other reason. is disposed at an 1 angle laterally across the rollers.

In the drawings:

FIG. I is a small scale perspective view illustrating the use of a holddown attachment embodying the invention in operative position on a bundle-stringing block;

FIG. 2 is a view similar to FIG. 1 with the holddown roller swung up to inoperative position;

FIG. 3 is an end elevation of the block of FIG. 1 on a larger scale with parts of the main frame broken away and parts in section and showing the holddown roller in operative position as a running board approaches;

FIG. 4 is a view like FIG. 3 showing the holddown roller in inoperative position after passage of the running board through the block; and

FIG. 5 is a rear elevation, as seen from the right side of FIG. 3, with the pulling line and a portion of a conductor groove in section and the outline of the running board shown in broken lines.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring more particularly to the drawings, reference numeral 11 indicates in general a multiconductor or bundlestringing block of any suitable construction having a frame which includes laterallyextending parallel head bars Y12 and 13 (FIGS. 3-5) secured together, as by means of bolts 14, and end members 15 rotatably supporting in well-known manner a roller or sheave means 16 comprising a central pulling groove 17 and a plurality of conductor grooves 18 spaced laterally therefrom and from each other. As is customary, the pulling groove 17 is steel lined to resist abrasion by a wire rope pulling line and, as illustrated in FIG. 5, the conductor grooves 18 are lined with neoprene, or the like, to prevent surface damage to the conductors during stringing. Any desired means may be employed to support or suspend the block 11 from the usual insulator means secured to a tower or supporting ground structure, that illustrated comprising a clevis 19 mounted on each bolt 14.

When so suspended, as shown in FIGS. 1 and 2, a pulling line 21 is passed through the throat of the block 11 defined by the frame members l2, l3, l5 and the sheave or roller means 16 for guiding engagement in the groove .17 to direct a running board 22 connected thereto through the stringing block throat to place conductors 23 secured to the running board properly in respective ones of the grooves 18, all as is well understood in the art of stringing high voltage transmission lines.

The illustrated embodiment of the instant invention comprises a holddown device for attachment to any such bundle or multiconductor stringing block which is made up of a holddown roller 24 for limiting upward movement of the pulling line 21 passing through the throat of the block, means rotatably supportingthe roller 24 in operative position in the throat and operable to move the roller to inoperative position to enable free passage of the running board 22 through the throat by the pulling line, and resilient means constraining the holddown roller toward and retaining the same in such operative and inoperative positions.

The means for rotatably supporting'the roller 24 comprises a mounting bracket 25 secured by bolts 26 (FIGS. 4 and 5) to the outer or rear face of the trailing head bar 13 having rearwardly extending end flanges 27 for supporting a pivot or hinge pin 28, and an auxiliary bracket 29 having parallel end links or legs 31 which are pivotally mounted at their upper ends on the pin 28, are connected together by an integral crossmember 32 intermediate their ends, and rotatably support the roller 24 at their lower ends in any suitable manner, as

by means of a roller axle 33. intermediate their ends, the forward edges of the legs 31 are provided with protuberances or stop lugs 34 for contacting the under surfaces of the transverse portion of the mounting bracket 25 and the head bar 13 to positively limit forward swinging of the auxiliary bracket 29 and roller 24 relative thereto in a clockwise direction on the pivot 28 as seen in FIGS. 3 and 4. The upper end surfaces 35 of the legs 31 similarly function as means for positively limiting swinging movement of the holddown roller 24 rearwardly and upwardly in a counterclockwise direction about pivot 28, as viewed in FIGS. 3 and 4, by contacting the outer or rear surface of the transverse portion of the mounting bracket 25.

The previously noted resilient means constraining the holddown roller 24 toward and retaining the same in such movement-limited operative and inoperative positions comprises a pair of coil springs 36. The upper end of each spring is anchored at 37 by a rearwardly and outwardly extending car 38 at the upper end of an end flange 27 on the mounting bracket 25. The lower end of each spring 36 is anchored at 39 to a rearward and outwardly directed extension 41 of the lower end of the associated leg 31 of the auxiliary bracket 29. It thus will be seen from FIGS. 3 and 4 that each spring 36 applies a constraining force along a line extending between the anchor points 37 and 39 which is shiftable to opposite sides of the pivot 28. Consequently, when the holddown roller 24 is in its operative position of FIGS. 1 and 3, that line of force exerted by each spring 36 is forward of the pivot 28 and the springs resiliently retain the stop lugs 34 against the under surfaces of 13 and 25, while the lines of force exerted by springs 36 are on the opposite side or rearward of pivot 28 when the holddown roller 24 is in its inoperative position of FIGS. 2 and 4 to retain the upper stop surfaces 35 against the rear transverse surface of mounting bracket 25 As shown in FIGS. 5, the holddown roller 24 is centrally disposed laterally in the throat of the bundle block 11 in vertical alignment with the pulling line groove 17, and the periphery of roller 24 decreases in diameter from its ends which are in close proximity to the sheave means 16 when in lower or operative position. In fact, it is preferred that the end portions of the roller 24 be disposed in the conductor grooves 18 laterally adjacent the pulling line groove 17. The spacing between rollers 16 and 24 in such operative position of the latter is such as normally to limit lateral as well as vertical movements of the pulling line 21. But under some conditions of operation, as by virtue of twisting or yawing of the bundle block 11 about its verticalaxis, the pulling line 21 may be drawn or disposed at an angle laterally across the rollers 16 and 24 and pulled into contact with both of them simultaneously. This can result in the two counterrotating surfaces of the rollers trapping orjamming the pulling line to squeeze the same therebetween and throw it laterally past the roller 24 or trip the holddown device prematurely to its inoperative positron.

To obviate any such malfunctioning, auxiliary guide means 62 are provided for preventing contact of the pulling line 21 simultaneously with the sheave or roller means 16 and the holddown roller 24. As best seen in FIGS. 3-5, this guide means 42 is mounted at its upper end on the pivot pin 28 with laterally spaced depending guards 43 extending into close proximity to sheave 16 at their lower ends when the roller 24 is in its lower operative position. The forward edges of the guards 43 extend inwardly of the periphery of the outer ends of the holddown roller 24, being shaped to conform closely to the tapered roller surface, and these guards 43 are joined by an integral transverse portion 44 which is secured to the crossmember 32 of the auxiliary bracket 29 by a U-bolt 45.

In operation, after a holddown device as above described has been attached to a multiconductor block, the latter is suspended from or attached to insulator means on a tower or supporting ground structure in well-known manner and the pulling line 21 is engaged in and drawn through the groove 17, the holddown roller 24 being disposed in the throat of the bundle block in its lowermost or operative position of FIGS. 1, 3

and 5. As the pulling line is drawn through the stringing block, it will be confined to the space defined by the groove 17, the holddown roller 24 and the depending guards 43 of the guide means 42. The running board 22 thus will be sufficiently accurately aligned with the throat of the stringing block 11 as it approaches the same to prevent any damage to the block or resultingly, and more importantly, the conductors 23. As the running board 22 is pulled into the block 11, as best seen in FIG. 3, the leading end thereof will strike the roller 24 to move the latter against the restraining forces of the springs 36 rearwardly about the pivot 28. As the lines of force imposed by the springs 36 thus pass from their normal position of FIG. 3 rearwardly of the pivot 28, the springs will act to lift the holddown roller 24 to its upper inoperative position of FIGS. 2 and 4 and to retain the same therein. The instant holddown device thus functions to insure accurate presentation of the conductors 23 to their respective grooves 18, and it is tripped automatically by the running board to be moved to inoperative position after its function has been completed successfully to enable free passage of the running board through the stringing block, all without requiring the attendance of an operator.

We claim:

1. A holddown device for multiconductor stringing blocks having a frame rotatably supporting sheave means with conductor and pulling line grooves and defining a throat for passage of a running board interconnecting a pulling line and conductors being strung, comprising a holddown roller for limiting upward movement of said pulling line passing through said throat, means rotatably supporting said roller in operative position in said throat and operable to move said roller to inoperative position to enable passage of a running board through said throat by said pulling line, and resilient means constraining said holddown roller toward and retaining the same in said operative and inoperative positions.

2. A holddown device according to claim 1, wherein said means supporting said roller comprises a mounting bracket secured to said frame, and an auxiliary bracket carried thereby for rotatably supporting said roller, with said resilient means being interconnected between said brackets.

3. In a holddown device according to claim 2, means on said auxiliary bracket positively limiting movement of said holddown roller toward operative and inoperative positions.

4. A holddown device according to claim 2, wherein said auxiliary bracket is carried on a pivot by said mounting bracket, and said resilient means applies a constraining force along a line shiftable to opposite sides of said pivot.

5. In a holddown device according to claim 4, wherein said resilient means comprises springs connected at their ends to said brackets, means on said auxiliary bracket positively limiting movement of said holddown roller toward operative and inoperative positions by said springs.

6. A holddown device according to claim 1, wherein the periphery of said holddown roller decreases in diameter from the ends toward the center thereof and said ends are in close proximity to said sheave means when said roller is in operative position.

7. A holddown device according to claim 6, wherein said sheave means includes a said conductor groove laterally adjacent each side of said pulling line groove, and said ends of said holddown roller are disposed in said laterally adjacent conductor grooves when said roller is in operative position.

8. In a holddown device according to claim 1, auxiliary guide means for preventing contact of said pulling line simultaneously with said sheave means and said holddown roller.

9. In a holddown device according to claim 2, guide means carried by said auxiliary bracket for preventing contact of said pulling line simultaneously with said sheave means and said holddown roller when the latter is in operative position.

10. In a holddown device according to claim 7, auxiliary guide means attached to said auxiliary bracket comprising depending arms disposed closely adjacent the periphery of said sheave means on each side of said pulling line groove when said holddown roller is in operative position.

2% UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 584, 837 Dated June 15, 1971 Inventor(s) Frank Ward Reilly, Sr and Hoyt W. Bozeman, Jr.

It is certified that error appears in the above-identified patent and that: said Letters Patent are hereby corrected as shown below:

r- Col. 1, line 32, after "block" insert is lost and damage 1 to the conductors and the stringing block Col. 3, line 35, "FIGS should be FIG. Col. 3 line 56, "62 should be 42 Col. 4, line 7, after "importantly, insert to Signed and sealed this 16th day of November 1971.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. ROBERT GOTTSCHALK Attestine; Officer I Acting Commissioner of Patents 

1. A holddown device for multiconductor stringing blocks having a frame rotatably supporting sheave means with conductor and pulling line grooves and defining a throat for passage of a running board interconnecting a pulling line and conductors being strung, comprising a holddown roller for limiting upward movement of said pulling line passing through said throat, means rotatably supporting said roller in operative position in said throat and operable to move said roller to inoperative position to enable passage of a running board through said throat by said pulling line, and resilient means constraining said holddown roller toward and retaining the same in said operative and inoperative positions.
 2. A holddown device according to claim 1, wherein said means supporting said roller comprises a mounting bracket secured to said frame, and an auxiliary bracket carried thereby for rotatably supporting said roller, with said resilient means being interconnected betweeN said brackets.
 3. In a holddown device according to claim 2, means on said auxiliary bracket positively limiting movement of said holddown roller toward operative and inoperative positions.
 4. A holddown device according to claim 2, wherein said auxiliary bracket is carried on a pivot by said mounting bracket, and said resilient means applies a constraining force along a line shiftable to opposite sides of said pivot.
 5. In a holddown device according to claim 4, wherein said resilient means comprises springs connected at their ends to said brackets, means on said auxiliary bracket positively limiting movement of said holddown roller toward operative and inoperative positions by said springs.
 6. A holddown device according to claim 1, wherein the periphery of said holddown roller decreases in diameter from the ends toward the center thereof and said ends are in close proximity to said sheave means when said roller is in operative position.
 7. A holddown device according to claim 6, wherein said sheave means includes a said conductor groove laterally adjacent each side of said pulling line groove, and said ends of said holddown roller are disposed in said laterally adjacent conductor grooves when said roller is in operative position.
 8. In a holddown device according to claim 1, auxiliary guide means for preventing contact of said pulling line simultaneously with said sheave means and said holddown roller.
 9. In a holddown device according to claim 2, guide means carried by said auxiliary bracket for preventing contact of said pulling line simultaneously with said sheave means and said holddown roller when the latter is in operative position.
 10. In a holddown device according to claim 7, auxiliary guide means attached to said auxiliary bracket comprising depending arms disposed closely adjacent the periphery of said sheave means on each side of said pulling line groove when said holddown roller is in operative position. 